1. Field of the Invention
This invention relates to a vapor phase growth apparatus provided with a wafer holding table for supporting a semiconductor wafer in the internal of a reaction chamber and provided with a heater under the wafer supported on the wafer holding table for vapor phase growth on the surface of a wafer under a heated condition.
2. Description of the Related Art
A conventional vapor phase growth apparatus is disclosed in, for example, Japanese Patent Laid-open No. Hei 5-152207. In the vapor phase growth apparatus, a vapor phase growing film is formed by heating with a heating element supported by a wafer holding member and disposed under the wafer holding member. For example, a hollow cylinder extending upward is mounted on the bottom side of the base, and a heater supporter is mounted on the top of the cylinder. Above the heat supporter, a plate-like reflection plate is provided, the heater is accommodated within, and an equalizing plate is disposed at the top thereof. The top of the plate-like reflection plate is positioned above the equalizing plate, and on the top thereof a ring-like wafer holding table is engaged. On the inside periphery of the wafer holding plate, a back facing is formed, where the wafer is disposed.
The atmosphere in the reaction chamber of this vapor phase growth apparatus is reduced in pressure to 50-400 Torr, a large amount of feeding gas such as dichlorosilane and carrier gas such as hydrogen are introduced from the gas inlet, and the vapor phase growing operation is carried out, when the wafer is heated at a temperature of about 1150.degree. C.
A conventional vapor phase growth apparatus has a drawback in that a plate-like Mo reflection plate is provided under a heater, which causes impurity contamination on the heater, resulting in the serious reduction of heater life. This reduced heater life is a disadvantage of the conventional vapor phase growth apparatus. On the other hand, in the case of a reflection plate consisting of SUS and quartz, it is impossible to rinse out with an aqueous solution of HNO.sub.3 --HF after heat treatment, because the surface of the reflection plate is not resistant to the corrosion with the aqueous solution of HNO.sub.3 --HF.